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Fencer Vulns
critical 9.8

CVE-2020-27507 json

The Kamailio SIP before 5.5.0 server mishandles INVITE requests with duplicated fields and overlength tag, leading to a buffer overflow tha…

published 2023-03-15 3 y ago modified 2026-06-17 4 mo ago also EUVD-2020-20017

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 67%
public exploits
0
none known

Summary

The Kamailio SIP before 5.5.0 server mishandles INVITE requests with duplicated fields and overlength tag, leading to a buffer overflow that crashes the server or possibly have unspecified other impact.

Patch / fix

  • kamailio kamailio 5.5.0
  • kamailio Debian 14, Debian 13, Debian 12 5.4.2-1

debian advisories DEBIAN-CVE-2020-27507

  • kamailio Ubuntu Pro 16.04 LTS 4.3.4-1.1ubuntu2.1+esm1
  • kamailio Ubuntu Pro 18.04 LTS 5.1.2-1ubuntu2+esm1
  • kamailio Ubuntu Pro 20.04 LTS 5.3.2-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2020-27507

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
20 mo ago

Exploit prediction

1.18% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/kamailio/kamailio/issues/2503 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Classification

Weakness
  • CWE-120 Buffer Copy without Checking Size of Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.